Polyolefin members may be prepared by extrusion of a solution of polyolefin in a solvent followed by stretching. This process is referred to as the geltrusion processes, and leads to high strength fibrous materials, such as fibre, tape and sheet members. Geltrusion is fundamentally different from the other main processes for manufacturing high performance polyolefin fibres, such as melt spinning and solid formation. The geltrusion process for manufacturing of fibres is for example disclosed in EP 1 699 954 and for manufacturing of sheet members is for example disclosed in EP 0 500 173 and EP 0 504 954.